Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Honey, I Shrunk the Solar System or Pluto We Barely Knew Ye as a Planet Image credit JPL
The Way it Was… Image from JPL
And Then There Were Eight Image from JPL
From Where Did the Word Planet Come? • The word “planet” is derived from the Greek word for “wanderer” and was traditionally applied to any heavenly body that moved with respect to the stars. In this sense the Sun and Moon were also planets. • Dictionary says that a planet is any one of the nine large bodies that orbit the Sun. • But some objects have been found that are larger than Pluto- so are they planets?
Who Discovered the First Planets? • Ancient cultures knew that some objects were not fixed in the sky like the stars. • The Greeks knew of five such objects: Mercury, Venus, Mars, Jupiter and Saturn • By 800 B.C.E. Babylonian astronomers had records of planetary motion for Venus, Jupiter and Mars.
The Solar System Until 1781:Mercury, Venus, Earth, Mars, Jupiter and Saturn Images from NASA
The Solar System Grows: What to Name a New Planet? • March 13, 1781 William Herschel discovers what he thinks is a comet, but he has discovered a new planet- the seventh in our Solar System. • Herschel wanted to name the new planet George after King George III of England. • It was decided to continue with the Roman god names that had been used for the other planets, thus it was named Uranus. • This set the standard for the convention of using Roman god names for the planets.
Uranus- The First New Planet • Distance: 19.1 AU Doubled the size of the Solar System • Diameter: about 4 Earth diameters Image courtesy of NASA
Another New World: Neptune • The orbit of Uranus was not as expected. • John Couch Adams, a 24 year old Cambridge grad, thought that this might be caused by another unknown planet • In 1845 he submitted his calculations to the Astronomer Royal of England. English star charts not good enough. • At nearly the same time French astronomer Urbain Jean Joseph Le Verrier did the same calculations. The Berlin Observatory was given his data and the planet was found the first night due to better star maps.
Neptune • Following the Roman god theme the planet was named Neptune, for the sea god since it was blue • 30 AU from the Sun • Diameter: about 4 Earth diameters Image by Hubble Space Telescope
A Ninth Planet? • Speculations about a ninth planet date back to the late 1800’s. • Percival Lowell urged that a special camera be built to look for Planet X. • In 1929 the camera was finished and installed at Lowell Observatory in Flagstaff, AZ • Clyde Tombaugh discovered Pluto on February 18, 1930 after looking at over one million stars • Name Pluto suggested by Venetia Burney, an 11 year old girl. Pluto was the Roman god of the underworld.
Clyde Tombaugh 1906-1997 Left: Young Clyde Tombaugh at Lowell Observatory after the discovery of Pluto. Above: Dr. Tombaugh contemplates his discovery of Pluto during a 1988 visit to the Powell Observatory in Louisburg, Kansas. Photo credit Vic Winter
Finding Pluto Pluto images by Nathan Twining Observatory
Here it is! Pluto images by Nathan Twining Observatory
Pluto • 39.5 AU from Sun • Diameter: about 0.18 Earth diameter (about 1400 miles) • Pluto and Charon essentially a double system • NASA New Horizons mission will reach Pluto in 2015 • Pluto has been assigned asteroid number 134340 by the Minor Planet Center Image by Hubble Space Telescope
It is round like a planet and it orbits the Sun. Pluto very small Doesn’t fit into any other categories of planets- terrestrial or gas giants Orbit strange- tilted 17° from plane of the solar system May be typical of thousands of icy objects found far from the Sun The Arguments for and Against Planethood for Pluto Image by JPL
The Kuiper Belt John Hopkins University
The International Astronomical Union Resolution • A planet is for the first time defined scientifically. A planet orbits a star, has sufficient gravity to become round, and has cleared the neighborhood around its orbit. • A Dwarf Planet orbits the Sun, is not a satellite, has sufficient gravity to become round and has not cleared the neighborhood of its orbit. Pluto is the prototype of this class and currently includes Ceres and Eris. Others will be decided upon later. • A third class, Small Solar System Bodies, was defined as all other objects except satellites. This includes most asteroids, most comets and most trans Neptune objects.
And yet another change…. June 11, 2008 News Release - IAU0804: Plutoid chosen as name for Solar System objects like Pluto Plutoids are celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass so they have a near-spherical shape, and that have not cleared the neighborhood around their orbit. Satellites of plutoids are not plutoids. The two known and named plutoids are Pluto and Eris. Ceres is the only dwarf planet.
So Long Planet Pluto and Hello Plutoids! International Astronomical Union
The Public Responds This humorous image was created for a special “Save Pluto” contest held on www.worth1000.com in response to public outcry about the demotion of Pluto. It does not represent a real eventuality, but is used here to show how passionately people have responded to the change in Pluto’s status.